This invention relates to an improved pesticide composition and methods for its preparation and use. More specifically, this invention is directed to the use of purified water having low total dissolved solids for preparing application-ready pesticide compositions from pesticide concentrates. The use of purified water, optionally in combination with art-recognized polymer adjuvants and/or ammonia or ammonium salts, to formulate application-ready pesticide compositions provides enhanced pesticidal efficiency and efficacy with concomitant reduction in crop injury.
The use of pesticides, including both herbicides and insecticides, is an essential component of commercial farming operations. The presence of crop consuming insects and nutrient consuming weeds not only work to decrease crop yields, but infestations of such pests also leads to reduced crop quality. The use of pesticides in agricultural production has therefore become an essential aspect of commercial farming protocols. Yet the use of such pesticides is not without recognized disadvantages. The inherent phytotoxic activity of herbicides can lead to crop damage and reduced yield. Moreover, the environmental community is becoming more intolerant of increasing pesticide levels in rivers and streams due to xe2x80x9crun-offxe2x80x9d from pesticide treated crop areas.
Accordingly, there has been a significant research and development effort directed to improving pesticide efficiency generally and for crop-specific and/or target species-specific applications. Numerous adjuvants for preparing application-ready pesticide formulations have been developed and utilized commercially. Such adjuvants are typically combined with the active pesticide component(s) during preparation of the application-ready (tank mix) pesticide formulations. Such formulations are typically prepared from pesticide concentrates, each having label or package insert instructions for dilution with water to a prescribed concentration, often crop-dependent or target pest species-dependent, for application to crop areas infested with said species, at a prescribed, predetermined volume or weight per area rate. Such compositions are typically designated for pre-emergent or post-emergent application and they can be applied as a spray, injected into the soil, or wiped from a bar mounted wick directly onto the target plant species.
Many adjuvants have been developed with the goal of improving performance of aqueous pesticide formulations. Such adjuvants include surfactants which promote the spreading and retention of applied pesticide formulations on target plant species. Other adjuvants are detailed for minimizing the known deleterious efforts of water hardness on pesticide performance. Ammonia or ammonium salts have been used for improved pesticide uptake and various art-recognized agriculturally acceptable polymers are detailed for controlling size, drift and surface adherence of droplets as they are applied to crop areas. While the use of adjuvants for agricultural pesticide formulations provide advantage in numerous specific applications, their efficacy is significantly dependent on the species of pesticide, the source of water for diluting the commercial pesticide concentrate, the use of other adjuvants used in combination, and weather and soil conditions at the time of application and post-application. Further, the use of chemical adjuvants add to the crop management costs, and, like the pesticides they are intended to complement, adjuvants can themselves provide basis for additional concern from an environmental conservation perspective.
The present invention relates to novel pesticidal formulations which exhibit enhanced pesticidal efficacy without or with but selective use of art-recognized agricultural pesticide adjuvants. Most, if not all, commercial agricultural pesticides are provided as pesticide concentrates having label or package insert instructions for dilution with water to a prescribed concentration. The prescribed concentration is often dependent on the target test species and/or the crop species being treated to manage pest infestation. The label or package insert instructions for pesticide concentrates typically prescribe, as well, an application rate (volume of the diluted application-ready pesticide formulation per unit area of the locus of application to provide a predetermined weight of pesticide per acre).
In accordance with the present invention, the use of purified water to dilute pesticide concentrates provide application-ready pesticide formulations which exhibit enhanced pesticidal efficacy and when applied to the locus of crops, reduced crop damage. Water utilized to prepare application-ready pesticide compositions in accordance with this invention is purified to have a total dissolved solids (TDS) content of 1 to about 100 ppm. The resulting aqueous pesticide composition is characterized by enhanced pesticidal efficiency and reduced crop damage and therefore provides a greater margin for variability in application rate (volume or weight per unit area) during use of the pesticide formulation.
The improved pesticidal efficiency of application-ready pesticide formulations (tank mixes) prepared by diluting pesticide concentrates with purified water in accordance with this invention is such that the pesticide concentrate can be diluted with up to four times the volume of water appropriate to provide the prescribed concentration (where the application-ready tank mix is applied at the volume/acre rate specified for the prescribed concentration). Alternatively, or in addition, the present application-ready pesticide compositions can be applied at less than the predetermined volume per application area rate without compromise of pesticidal efficacy. Thus, regardless of how the pesticide is delivered/applied, the present invention allows it to be used at a less-than-label rate to the locus of target pest species without compromise of pesticidal efficacy.
While one object of this invention is to provide effective pesticidal formulations without use of costly adjuvants, it has been found that there are at least two art-recognized adjuvant classes that can be utilized to complement the efficiency realized with the use of low TDS water as a pesticide diluent in accordance with this invention: polymers which work to control droplet size, surface affinity, drift and drying, and ammonia or ammonium salts which are believed to work to enhance plant membrane transport of the pesticide.
Thus, in accordance with another embodiment of the invention there is provided an aqueous composition useful as a diluent for pesticidal concentrates to improve pesticidal efficiency and improve pesticidal performance, said composition consisting essentially of a mixture of purified water having 1 to about 100 ppm total dissolved solids and a water dispersible polymer at a concentration of about 0.075 to about 0.2% by weight per unit volume. Such aqueous composition can be formulated to include, as well, ammonia or an ammonium salt at a concentration of about 0.5 to about 4% by weight ammonia per unit volume, In a related embodiment there is provided an aqueous composition for use as a diluent for pesticide concentrates to enhance pesticidal efficiency of said pesticides wherein the composition consists essentially of a mixture of purified water having 1 to about 100 ppm total dissolved solids an ammonia or an ammonium salt at a concentration of about 0.5 to about 4% by weight ammonia per unit volume.
Another related embodiment of the invention is based on use of certain commercially available polymer adjuvants, particularly optionally derivatized polygalactomannans in aqueous pesticide compositions diluted in water to a concentration less than the prescribed concentration without loss of pesticidal efficacy. Polygalactomannans are the natural polymer components of plant derived gum; for example, gums derived from guar and tamarind. The use of guar gums as a drift control agent in pesticidal compositions is described and claimed in U.S. Pat. No. 5,550,224 the disclosure of which is expressly incorporated by reference. Such pesticide polygalactomannan formulations can also be formulated to include ammonia or an ammonium salt so that the composition includes about 0.5% to about 4% by weight ammonia per unit volume. Preferably the water used to dilute the pesticide concentrate is purified water having a total dissolved solids of 1 to about 100 ppm.
In an alternative, but related embodiment of the invention there is provided a method for improving crop coverage efficiency of a pesticide concentrate composition having label (or package insert) instructions for dilution with water to a crop dependent or a pest species-dependent concentration and a recommended volume per area application rate. The method includes the steps of diluting the pesticide concentrate with at least the label specified volume of water, adding about 0.5 to about 2.0 lbs. of an optionally derivatized polygalactomannan composition per 100 gallons of water used to, and applying the diluted pesticide composition to the locus of crops at less than the recommended volume per acre so that the application rate per acre of the pesticide is less than 95% of the label-specified application rate.